Air preheater for boiler installations



Oct. 15, 1929. c. w. E. CLARKE AIR PREHEATER FOR BOILER INSTALLATIONS Filed Feb. 20, 1925 2 Sheets-Sheet 1 %1 abtoame Oct. 15, 1929. c. w. E. CLARKE AIR PREHEATER FOR BOILER msmmuzous .Filed Feb. 20, 1923 2 Sheets-Sheet 2 2 (June/W500 $1,1 1 cu We fatented Oct. 15 1929 STATES CHARLES W. E. CLARKE, OF NEW YORK, N. Y.

AIR PREI-IEATER FOR BOILER INSTALLATIONS Application filed February 20, 1923.

This invention relates to apparatus designed to utilize waste heat from a boiler to preheat the air used for combustion or other purposes.

While it has been proposed heretofore to preheat the air used for combustion in the furnace of a boiler, no entirely satisfactory arrangement for accomplishing this object has been devised, so far as I have been able to learn. It is the chief object of the present invention, therefore, to devise a satisfactory solution for this problem. The invention involves both a novel organization of parts and also a novel construction of preheater.

The nature of the invention will be readily understood from the following description when read in connection With the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.

Referring now to the drawings,

Figure 1 is a view, largely diagrammatic, of a boiler installation equipped with a pre heating apparatus embodying this invention;

Fig. 2 is a cross sectional view on the line 2-2, Fig. 1;

Fig. 3 is a cross sectional view on the line 33, Fig. 1; and

Fig. 4 is an enlargement of a small section of Fig. 3.

Referring more particularly to Fig. 1, it will be seen that the more important parts of a modern boiler installation are shown diagrammatically, the furnace walls being indicated at 2 and 3, the stoker grate at 4, baffles at 6 and 7, and parts of the flue gas uptake at 8 and 9. Located above the boiler in the uptake for the flue gases is the pre heater provided by this invention and indicated in general at 10.

The preheater comprises an upper header or bustle pipe 12, a lower header or bustle pipe 14, and a series of plates 16 which connect the two headers and form two preheater sections with a space 15 constituting a bypass between these sections. Referring more particularly to Figs. 2, 3 and 4, it will be seen that the upright connecting plates 16 are arranged to provide alternate air spaces 17 and flue gas spaces 18, these spaces Serial No. 620,162.

being separated from each other by the plates. The air spaces 17 open at their ends in the headers 12 and 14, respectively, while the flue gas spaces 18 communicate at their lower ends with the space in the uptake memher 8, and at their upper ends with the space in the uptake member 9. The construction will be evident from an inspection of the drawings.

For the purpose of controlling the flow of the flue gases through the by-pass 15, a pivoted damper 20, Fig. l, is. located in the by-pass where it may either open or close this passage.

Air may be forced through the preheater either by suction or pressure. In the arrangement shown, the pressure end of a blower 21 is connected withthe upper header 12 and forces air through this header and through the air spaces 17 into the lower header 14, and thence through a conduit 22 to the stoker wind box 24. In some cases it is preferable to locate the blower at some intermediate point between the preheater and the stoker wind box, in which case the air is forced through the preheater by suction. In such an arrangement the upper header 12 may be omitted.

When the apparatus is in operation, the damper 2O normally is closed, or nearly so, and practically all of the flue gases flow through the preheater, where they give up part of their heat to the air passing in the opposite direction through the preheater. Due to the peculiar construction of the preheater, a very large heat absorbing surface is provided in a structure of relatively small dimensions. A large flow of air, therefore, may be heated to a relatively high temperature. Whenever the boilers must be worked to high capacity, the damper 20 is opened, thus increasing the draft, due partly to the reduced resistance to the upward flow of flue gases, and partly, also, to the increased temperature of the flue gases flowing through the stack.

The invention therefore provides a simple form of preheating apparatus. which may be manufactured and installed economically, which effectually raises the temperature Having thus described my invention, what I desire to claim as new is:

1. In a boiler installation, the combination of an air preheater comprising two vertical stationary preheater sections located in the path of the flue gases and spaced apart to provide a by-pass for the flue gases between them, a damper movable to open or close said by-pass, means for conducting air away from the preheater, and a blower for forcing air to be heated through both of said preheater sections simultaneously and into said conducting means. I

- 2. Inaboiler installation, the combination of an air preheater located in position to absorb heat from the flue gases, said preheaterconsisting of two parallel sections spaced apart to provide a bypass between them, each of said sections comprising a series of vertical plates arranged to provide spaces alternating with flue gas spaces, means for conducting air away from said preheater, a blower for forcing air through said preheater and said conducting means, anda damper controlling the flow of flue gases through said by-pass.

3 The combination with a boiler installation including a flue gas uptake leading upwardly from the boiler, of an air preheater located above the boiler and in said uptake,

said preheater consisting of two sections spaced apart to provide a by-pass for flue gases between them, each of said sections comprising a series of plates arranged to provide upwardly directed flue gas spaces altermating with air spaces, with said air spaces opening laterally near the top and bottom of the preheater, upper and lower headers connected by said air spaces, a conduit connected With one of said headersto conduct air away from the preheater, a blower for forcing air through said preheater, and a damper for controlling the flow of flue gases through said by-pass.

4. The combination with a boiler installa- I tion including a fiue gas'uptake leading upwardly from the boiler, of an air preheater located above the boiler and in said uptake;

said preheater comprising two stationary preheater sections, a caslng cooperating with said sections to hold them spaced apart to provide a by-pass for flue gases between them, each of said sections comprising a series of substantially upright plates arranged to provide air spaces alternating with flue gas spaces through which the flue gas can iiow upwardly through the preheatcr, upper and lower headers into which said air spaces open laterally near the top and bottom of the preheater; and conduits connected with said headers for conducting air to and from said headers.

CHARLES W. E. CLARKE. 

